the formula for the Area of a trapezoid is A = h (b1 +b2)/2
we are given that A = 6000f2
we are told that h = width of back yard
let b1 = width of front yard, then back yard = 2b1, and h = 2b1
so, 6000f2 = 2b1 ((b1 + 2b1)/2
which becomes 6000f2 = 3b12
2000f2 = b12
b1 ≅ 44.72f
Proof: 6000f2 = 2•44.72((44.72 + 89.44)/2) = 89.44•67.08 = 6000f2